For an on-vehicle air conditioner, space saving is required to accommodate pieces of equipment in a vehicular engine room. To meet this requirement, in recent years, there has been provided an integrated electric compressor in which a compressor constituting the on-vehicle air conditioner, a motor for driving the compressor, and a driving board for driving the motor are integrally accommodated in a housing.
In such an integrated electric compressor, since a floating capacity Cf is present between a motor 5 and a housing as shown in FIG. 6, if a power supply voltage supplied to the motor 5 is caused to fluctuate by the switching action of a switching element 4 of a driving board 1, a leakage current flowing from the motor 5 to the housing is generated. Since this leakage current produces radio noise, a proposal has been made that by providing common mode capacitors 2 and a common mode coil 3 on the driving board 1, a loop formed by the leakage current is made small in the case where the voltage supplied to the motor 5 is caused to fluctuate by the switching action of the switching element 4, by which an influence of radio noise is reduced.
Patent Document 1: Japanese Patent Laid-Open No. 2006-27315